The present disclosure relates in general to semiconductor manufacturing technology, and more particularly, to reducing or solving precipitate defects associated with photolithography photomasks.
Photomasks, or reticles, are commonly used for photolithography in semiconductor manufacturing. Photomasks are typically made from very flat pieces of quartz or glass with a layer of chromium deposited on one side. The pattern being used to transfer an image to a wafer on BIM (Binary Mask) or PSM (Phase Shift Mask) masks during a photolithography processing. While contamination of photomasks has always been a problem, high precision masks, such as are used in photolithography having wavelengths equal to or less than 248 nm, are particularly susceptible to defects.
One type of photomask contamination is referred to as haze contamination. Haze contamination is a precipitant formed from mask cleaning chemical residual or impurity of fab or tool environment cross exposure. For example, when a solution including ammonium (NH4) and sulfate (SO4) is used to clean a photomask, contamination becomes apparent when the photomask is exposed to a short wavelength UV light, such as 248 or 193 nm.
Therefore, what is needed is a simple and cost-effective method and system that minimizes haze contamination.